fix: correctly claim capability for mock module, handle genesis expor…

…ts (#921)

## Description

This contains two fixes:
- the capability being claimed by the scoped keeper was incorrect (mock.ModuleName -> port ID)
- the mock module wasn't accounting for non empty genesis state in capabilities (after genesis export, capability will create the bound ports so rebinding doesn't need to happen)

closes: #XXXX

---

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- [ ] Targeted PR against correct branch (see [CONTRIBUTING.md](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [ ] Code follows the [module structure standards](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules/structure.md).
- [ ] Wrote unit and integration [tests](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#testing)
- [ ] Updated relevant documentation (`docs/`) or specification (`x/<module>/spec/`)
- [ ] Added relevant `godoc` [comments](https://blog.golang.org/godoc-documenting-go-code).
- [ ] Added a relevant changelog entry to the `Unreleased` section in `CHANGELOG.md`
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- [ ] Review `Codecov Report` in the comment section below once CI passes

testing/mock/mock.go

@@ -43,6 +43,7 @@ var _ porttypes.IBCModule = IBCModule{}
 // PortKeeper defines the expected IBC port keeper
 type PortKeeper interface {
 	BindPort(ctx sdk.Context, portID string) *capabilitytypes.Capability
+	IsBound(ctx sdk.Context, portID string) bool
 }
 
 // AppModuleBasic is the mock AppModuleBasic.
@@ -123,10 +124,10 @@ func (am AppModule) RegisterServices(module.Configurator) {}
 // InitGenesis implements the AppModule interface.
 func (am AppModule) InitGenesis(ctx sdk.Context, cdc codec.JSONCodec, data json.RawMessage) []abci.ValidatorUpdate {
 	for _, ibcApp := range am.ibcApps {
-		if ibcApp.PortID != "" {
+		if ibcApp.PortID != "" && !am.portKeeper.IsBound(ctx, ibcApp.PortID) {
 			// bind mock portID
 			cap := am.portKeeper.BindPort(ctx, ibcApp.PortID)
-			ibcApp.ScopedKeeper.ClaimCapability(ctx, cap, host.PortPath(ModuleName))
+			ibcApp.ScopedKeeper.ClaimCapability(ctx, cap, host.PortPath(ibcApp.PortID))
 		}
 	}